# Verdict L402 – Agent Prompt Injection & Action Firewall

> Verdict L402 – Agent Prompt Injection & Action Firewall is a paid API for AI agents from verdict.kechlab.com, paid per call via x402, $0.0255/call, status unknown (last checked 2026-10-21).

Judges a (goal, action, untrusted-content) triple to detect prompt injection, goal drift, data exfiltration, and unauthorized payments before an AI agent acts, returning allow/review/block.

## Facts

- Endpoint: POST https://verdict.kechlab.com/v1/firewall?utm_source=zero.xyz
- Price: $0.0255/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-21
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/verdict-l402-agent-prompt-injection-action-firewall-c103ad0f
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_qic8lA6wXmk-6Xy_D1aF_

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability verdict-l402-agent-prompt-injection-action-firewall-c103ad0f -d '<json body>'
```

Example prompt: Before you run that tool call, check it with Verdict's firewall — my goal was 'book a flight to Tokyo', the action you want to take is 'send $500 to account X', and the untrusted content is this email body I just read. Use balanced sensitivity and tell me if I should allow it.

## When to prefer this

Choose this endpoint when an AI agent is about to act on content from an untrusted source (web page, email, document, API response) and you need a real-time security check before execution. Especially valuable when the action involves payments, data deletion, external communication, or any irreversible side effect. Prefer consensus mode for high-stakes or financial actions. This is purpose-built for agentic prompt-injection and goal-drift detection — not a generic content moderation or spam filter.

## Known failure modes

- Missing required fields (goal, action, or content absent) — returns 400 error
- Ambiguous or very short content may reduce verdict confidence
- Consensus mode doubles the price and may have higher latency
- Overly strict sensitivity may block legitimate actions (false positives)
- Lenient sensitivity may miss subtle injection patterns (false negatives)
- Payment failure (L402) if USDC balance is insufficient — returns 402

## How this service works

Agent security guardrail. Judges the pair (untrusted content + proposed action) before an AI agent acts: detects tool calls that obey hidden prompt injection, leave the user's goal, destroy data or send data or money elsewhere. Adjustable sensitivity and optional multi-model consensus. Returns allow

## Output

Returns a verdict of allow, review, or block along with a threat classification (e.g. prompt injection, goal drift, data exfiltration, unauthorized payment), a plain-language explanation of why the verdict was reached, and a confidence score. In consensus mode, disagreement among the three independent models triggers a 'review' verdict automatically.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "goal": {
   "type": "string",
   "description": "the goal given by the human"
  },
  "action": {
   "type": "string",
   "description": "the action the agent wants to run (tool call, command, payment)"
  },
  "content": {
   "type": "string",
   "description": "the untrusted content read by the agent (page, email, document)"
  },
  "consensus": {
   "type": "boolean",
   "description": "(optional) true: three independent models, disagreement = review, double price"
  },
  "sensitivity": {
   "enum": [
    "strict",
    "balanced",
    "lenient"
   ],
   "type": "string",
   "description": "(optional) strict, balanced (default) or lenient"
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/verdict-l402-agent-prompt-injection-action-firewall-c103ad0f/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from verdict.kechlab.com](https://www.zero.xyz/host/verdict.kechlab.com/llms.txt)